Means for controlling the tension of a tennis-racket stringing



' r 1,635,943 July 12, 1927. w A LARNED I MEANS FOR CONTROLLING THETENSION OF A TENNIS RACKET STRINGING Filed Jan. '2, 1924 [UM CLEMWQINVENTOR Patented July 12, 1927.

UNITED STATES g 1,635,943 PATENT OFFICE.

WILLIAM-A. LARNED, F sU Mrr, NEW JERSEY, ASSIG-NOR TO THE DAYTON sTEELRAGQUET coivirnngor DAYTON, oHIo,

A CORPORATION OF OHIO.

MEANS FOR CONTROLLING THE TENSION OF A TENNIS-RACKET STRINGING.

iipplicationfiled January 7, 1924. Serial No. 684,810.

This invention relates to new and useful improvements 111 tennisrackets, and refers more particularly to a novel method of, and.

means for, controllin the tension of the l stringing of the frame.

It is the principal object of my invention to control the tension of thestringing of a steel or wood tennis racket by increasing or decreasingthe strung area enclosed byv the frame. I v

To do this, I provide means for increasing the area referred to, butwith provisions for preventing a counteracting change in the shape ofthe frame such as would tendto neutralize the effect of theareaincreasing means. i i

As. an area-increasing means, I adopt an expansion joint or,turnlnicklelocated at the top of the racket frame; but I have found thatwhen this turnbuckle is thus placed at the end of the major axis of theframe, and is then used to expand the area, it is necessary to have thelong strings of the racket run parallel to this major axis, with thecross strings perpendicular thereto. The long strings thus act as ananchorage to prevent a neutralizing distortion of the frame, such forexample, as would occur if the stringing were diagonal. Thisconstruction serves to prevent the tendency of the frame to become moreelliptical when under tension which would decrease its area, since, asis well known, a true circle is the maximum area for a given perimeter.

In the accompanying drawings illustrating my invention, Figure 1 is afront elevational View of a rectangularly strung, oval tennis racketcontaining a turnbuckle in its divided head. Figure 2 is an enlargedfront elevational view of the top of the racket frame, with theadjusting device shown in section. Figure 3 is a cross sectional viewtaken through said adjusting device on the line 33 of Figure 2, showinga turning instrument applied to it; Figure 4is a longitudinal sectionalview of a turnbuckle device in which cup nuts are fitted over the endsof the frame to dispense with a separate screw. And Figure 5 is alongitudinal sectional view taken through a turnbuckle device eniployingcup nuts with which the tubular frame ends have a cone connection- IWhile my improved string tensioning means may be employed ina tennisracket frame made of steel, wood or other material,

I have illustrated in thedrawingsa tubular steel frame 1 having legs 2,2 to which a wood handle 3 is secured.

na l axis to provide two free tubular ends 4, 4 in which are brazed orotherwise tightly secured, nuts 5, one'with a right and the other with aleft thread. These nuts receive the threaded ends ofa screw 6 to which acentral web 7 of a turnbuckle sleeve 8 is pinned. The hollow ends-ofthis sleeve 8 enclose. the tubular frame-ends 4, 4, with its central web7 between them, said frame ends adapted to be moved away from each otherwhen the screw 6 is turned by the sleeve in one direction, and to bedrawn toward each other when the screw is rotated by the sleeve in theopposite direction. This sleeve 8 is formed with radial holes 9 toreceive the toothed projection 10 of a spanner wrench 11 or othersuitable instrument by means of which it may be easily turned to expandor contract the frame 1 for the purpose of controlling the tension ofthe stringing now to be described. (See Figures 2 and 3.)

In Figures 1 and 2 I have shown t-heform of stringing which I haveadopted, viz, a rectangular one having horizontal strings 12 andvertical strings 13, the latter servin to anchor the top of the frame asreferred to above. The principal expansion of the frame by turning vtheturnbuckle will be in the CllI'GClJ-lOD of its minor axis, thus mostefliciently increasing its total area, and tightening the strings.

These vertical strings prevent the frame from becoming more ellipticalin shape as it otherwisewould tend to do under this-increased pressure,as for example, with diagonal stringing. Any such effect of making theshape more elliptical would neutralize the string-tensioning effectproduced by the expansion oint.

In Figure 4 I have shown for use in the top of the frame, a turnbucklein which the central screw is eliminated. This construction comprisestwo cupped nuts 14, 14-that are firmly applied to the ends 4, 4 of thetubular frame 1. These nuts, one of which is provided with a right andthe other with a left external thread, are encircled by an internallythreaded turnbuckle sleeve 15 which, when it is turned in one direction,will force the nuts outwardly to move the ends 4, 4 of the frame apart,and when turned in the op- V p The frame 1 issplit or divided at the topon its longitudiposite direction, it will cause the nuts to draw theframe ends together for the purpose of controlling the tension of thestrings.

Still another form of turnbuckle is illustrated in Figure 5. In thisconstruction the central screw is also done away with, nuts 16, 16 withconical holes extending through them being employed to receive the ends4., 4. of the tubular frame. In this instance, these frame ends areclosed in to conical form so that the nuts may be firmly applied tothem. They are also surrounded by a turnbuckle sleeve 17 which may beturned to force them apart or to draw them together to vary the area ofthe frame for the purpose of controlling the tension of its stringing asbefore described.

N o matter what form of turnbuckle or expansion joint construction isemployed, if it is located in the outer end of the frame on itslongitudinal axis, and the stringing is arranged in the frame in such amanner as to anchor its outer end against undue extension when itsdivided ends are forced outwardly by the turnbuckle, the area of theframe will be increased and the stringing tightened.

As shown in Figures 1 and '2, I have provided an additional stringingfeature for the particular two vertical strings which are nearest to thevertical axis. According to this feature, these two strings 20 and 21are crossed over each other near the top, and likewise both crossed overthe uppermost horizontal strin 12, and then led downward to the throatof the racket. The advantage of this is that the uniformity of the meshis preserved, although of course this could be done in a variety ofways, such as by an ordinary loop or other method of tying, to bringthese two central vertical strings into proper alignment at the top.Incident to this there of course follows a better tension- In testimonywhereof I have hereunto set my hand this 2nd. day of January, 1924.

, WILLIAM A. LARNED.

